Electric starting mechanism for internal combustion engines



Feb. 1, 1966 D. WHEATLEY 3,232,123

ELECTRIC STARTING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed April 19, 1963 2 Sheets-Sheet 1 \m 4 A, V N n \Q% 3 1 mm N r 1 3% I Q i. kw Q Q N i f m N N. R N Z .5 E Xv? 1% Q N$ N QQN w Feb. 1, 1966 D. WHEATLEY 3,232,123

ELECTRIC STARTING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed April 19 1963 2 Sheets-Sheet 2 United States Patent 3,232,123 ELECTRIQ STARTING MECHANISM FUR INTERNAL COMBUSTION ENGKNES Denis Wheatley, New Maiden, England, assignor to C.A.V. Limited, London, England Filed Apr. 19, 1363, Ser. No. 274,161 Claims priority, application Great Britain Apr. 26, 1962, 15,323/62 2 Claims. (Cl. 747) This invention relates to starting mechnism for internal combustion engines, and of the kind comprising an electric motor having a rotor from which extends a shaft carrying a pinion adapted to be moved axially along the shaft into engagement with a toothed wheel of an engine with which the mechanism is associated, the end of the shaft remote from the rotor being supported within a bearing carried by a part connected to the motor casing.

The object of the invention is to provide such mechanism in a convenient form.

According to the invention a starting mechanism of the kind specified comprises a tubular rotor spindle into which the shaft extends, said spindle extending from the end of the rotor remote from the shaft, and being supported about a bearing carried by an end closure member of the motor casing.

In the accompanying drawings FIGURES 1 and 2 respectively are sectional side and end views of an example of the invention, FIGURE 1 being a section on the line 1-1 of FIGURE 2, and FIGURE 2 being a section on the line 2-2 of FIGURE 1.

Referring to the drawings there is provided a substantially cylindrical casing in which are mounted the stator windings 11 of an electric motor. The rotor 12 of this motor is mounted on a tubular spindle 13 surrounding a central shaft 14. One end of the spindle 13 is co-terminous with the adjacent end of the rotor (hereinafter termed the front end), whilst the rear end of the spindle extends from the rear end of the rotor and has mounted thereon a commutator 15. Also the rear end of the spindle 13 surrounds a bearing bush 16 carried by a central spigot 17 extending forwardly from the interior of a cap 18 forming a rear end closure for the casing 10.

The rear end of the shaft 14 incorporates splines which are formed at a very large helix angle so as to provide an interference engagement with splines in the spindle 13 so as to prevent both axial and angular movements. The shaft 14 extends forwardly to a substantial distance beyond the forward end of the motor 12 to provide an extension 14a which at its forward end is mounted in a bearing 19 in a cover 20 connected to the casing 10. Moreover, within the middle portion of the rotor (considered in an axial direction) the shaft 14 is waisted so as to provide a substantial clearance between the spindle 13 and shaft to render the shaft torsionally resilient to a fairly high degree.

A portion of the extension 14a between the front hearing 19 and the rotor 12 has formed on it a quick pitch screw-thread having a helix angle of approximately 60. With this portion of the shaft is engaged a complementary screw-thread formed on the interior of a sleeve 21 surrounding the extension 14a. On the front end of the sleeve is formed a pinion 22 which is adapted to be moved axially into engagement with a toothed flywheel 23 or" the engine with which the starter mechanism is associated.

In the cover 20 is mounted the winding 24 of a solenoid. The armature 25 of the solenoid, which is loaded rearwardly by means of a coiled compression spring 26, surrounds the sleeve and is of tubular cylindrical form hav- 3,232,123 Patented Feb. 1, 1966 ing a step 25a on its internal periphery. An annular ring 27 is normally held against the step 25a by means of a coiled compression spring 28 reacting at its other end on an abutment within the rear end of the armature. Moreover, the inner edge of the ring 27 is disposed to contact an abutment ring 29 located on the sleeve 21, when the armature is drawn into the winding against the action of the spring 26.

The cover 20 is provided at its rear end with a flange which is connected by screws to a mounting plate 30, the flange and plate being provided with registering holes for the reception of bolts whereby the mechanism can be mounted on the engine. Since in use, the bolts will serve to clamp the flange and plate together the aforesaid screws may be relatively small. The mounting plate 30 is secured to the casing by means of a pair of relatively long bolts 31 extending through the stator core and rear end cap 18, but between the mounting plate and the casing is interposed a hollow cylindrical part 32 formed from a transparent material such, for example, as a polycarbonate. Th ends of the part 32 have integral dowels engaging holes in the casing 10 and plate 30 respectively so that when the long bolts 31 are in position, the part 32 constitutes a rigid forward extension of the casing through which the rear end of the sleeve and other associated parts to be referred to can be viewed.

The pair of long bolts 31 are disposed at 180 to one another relative to the axis of the shaft, and pivoted about their rearward end portions within the cap 18 are a pair of brushes 33 co-operating with the commutator 1S and connected to the field windings. Another pair of brushes 33a disposed at 90 to the pair 33 are mounted about pivots 34 extending from an annular carrier 35 through which the bolts 31 extend and clamped in position by the cap 18, the brushes 33a being earthed.

On the mounting plate 30 is the fixed contact 36 of a motor controlling switch, the moving contact 35a of this switch being carried from the rear end of the armature 25 and being arranged to close the switch when the arma ture has been fully drawn forwardly into the winding 24.

Surrounding the rear portion of the sleeve 21 is a collar 37 which is urged forwardly by a coiled compression spring 38 interposed between it and an abutment ring on the sleeve. The internal periphery of the collar at its front end is of truncated conical cam form, and surrounds a plurality of angularly spaced balls 39 located respectively within holes in the sleeve 21. When the sleeve is at its rearward position the balls 39 are held by the collar in engagement with a circumferential groove 40 in the shaft to locate the pinion against inadvertent engagement with the flywheel. However, in the forward position of the sleeve the balls are urged by the collar into a corresponding number of recesses 41 in the shaft to locate the pinion against premature disengagement from the flywheel.

In use, when it is required to start the engine a remotely disposed switch is closed to energize the solenoid winding 24 thus drawing the armature 25 forwardly against the action of the spring 26. During this movement of the armature contact between the ring 27, and the abutment ring 29 causes the sleeve 21 to be pushed forwardly partially to engage the pinion 22 with the flywheel 23. During this axial movement angular movement is imparted to the pinion 22 by the quick pitch screw thread engagement between the sleeve and shaft. When the armature 25 has moved fully into its winding the switch contacts 36, 36a are closed to start the motor and the pinion is moved into full engagement with the flywheel by the action of the quick pitch screw thread.

In the event of a tooth of the pinion 22 engaging a tooth of the flywheel 23 end-to-end the armature 25 can still move fully into its winding due to the permitted axial movement of the. ring 27 against the action of the spring 28. Thus the motor will be started and will cause the pinion to be rotated until partial engagement is effected by the spring 28' whereafter full engagement is effected by the quick-pitch screw thread.

When the engine is started, and the remotely disposed switch is opened, the armature 25 will return to its original position under the action of the spring 26 and will urge the collar 37 in a direction away from the pinion to allow the balls to be moved out of the recesses d1. At the same time the switch contacts 36, 36a will be opened and the. pinion will be moved out of engagement with the flywheel, partly' by the action of the spring 26 acting on the sleeve via the armature 25, the ring 27 and the collar 37, and partly by the action of the quick pitch screw thread. When the sleeve has fully returned to its initial position the balls 39 will re-engage with the groove 40 in the shaft to prevent inadvertent re-engagement of the pinion with the flywheel.

. Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. The combination with an internal combustion engine having a fiywheel associated therewith, of a starting assembly therefor, said starting assembly comprising a hollow motor casing, a pair of end closure members for closing opposite ends of the casing respectively, a spigot member mounted on one of said closure members extending in a direction towards the other closure member, a tubular rotor spindle mounted at one end thereof for rotation about said spigot member and extending towards the other end closure member, a shaft accommodated within said rotor spindle and extending therefrom towards said other end closure member, means drivingly connecting said shaft with said spindle, bearing means carried by the other end closure member for supporting the shaft for rotation relative to said other end closure member, a motor rotor structure mounted on said spindle,

4 a stator structure mounted within the casing, and gear means on said shaft for coaction with said flywheel.

2. The combination with an internal combustion engine having a toothed flywheel associated therewith, of a starting assembly therefor, said starting assembly comprising a hollow motor casing, a cap closing the end of the easing, a closure member closing the opposite end of the casing, a spigot member mounted on said cap and extending towards the other end closure member, a tubular rotor spindle mounted at one end thereof for rotation about said spigot member and extending towards the closure member, a shaft accommodated Within the rotor spindle and extending therefrom towards and through said closure member, means coupling the shaft and spindle for rotation as a unit, bearing means carried by the closure member for supporting said shaft for rotation relative to said closure member, a pinion mounted on said shaft for coaction with said flywheel, coupling means interconnecting the pinion and the shaft for permitting axial movement of the pinion on the shaft and at the same time enabling the pinion to be driven by the shaft, means for moving the pinion axially into engagement with the toothed flywheel, a rotor structure mounted on said rotor spindle, a commutator mounted about said one end of the spindle, said commutator having electrical connection with the rotor structure, brushes mounted Within the cap for co-operation with the commutator and a stator structure mounted within the casing.

References Cited by the Examiner UNiTED STATES PATENTS 628,014 7/1899 Reston 74- 6 X 1,385,983 8/1921 Conrad 746 X 1,797,577 3/1931 Hoffman 746 2,831,352 4/1958 Elliott et al. 746

BROUGHTON G. DURHAM, Primary Examiner.

T. W. SHEAR, Assistant Examiner. 

1. THE COMBINATION WITH AN INTERNAL COMBUSTION ENGINE HAVING A FLYWHEEL ASSOCIATED THEREWITH, OF A STARTING ASSEMBLY THEREFOR, SAID STARTING ASSEMBLY COMPRISING A HOLLOW MOTOR CASING, A PAIR OF END CLOSURE MEMBERS FOR CLOSING OPPOSITE ENDS OF THE CASING RESPECTIVELY, A SPIGOT MEMBER MOUNTED ON ONE OF SAID CLOSURE MEMBERS EXTENDING IN A DIRECTION TOWARDS THE OTHER CLOSURE MEMBER, A TUBULAR ROTOR SPINDLE MOUNTED AT ONE END THEREOF FOR ROTATION ABOUT SAID SPIGOT MEMBER AND EXTENDING TOWARDS THE OTHER END CLOSURE MEMBER, A SHAFT ACCOMMODATED WITHIN SAID ROTOR SPINDLE AND EXTENDING THEREFROM TOWARDS SAID OTHER END CLOSURE MEMBER, MEANS DRIVINGLY CONNECTING SAID SHAFT WITH SAID SPINDLE, BEARING MEANS 